1. Field of the Invention
The invention relates to clutches which are operated automatically by centrifugal force at a predetermined speed of rotation so as to connect a driving member to a driven member or load. More particularly, the invention relates to a centrifugal clutch construction of the type having a pair of pivotally mounted clutch shoes which swing outwardly into coupling engagement with a driven clutch member and in which a stop projection is formed integrally on each of the clutch shoe webs for engagement with a hub when the shoes return to a fully disengaged position.
2. Description of the Prior Art
There are numerous types and arrangements of centrifugal clutch constructions in which one or more clutch shoes are retained in retracted position by springs until sufficient centrifugal force acts on the shoes to overcome the force of retaining springs, whereupon the clutch shoes pivot and swing outwardly and engage a stationary clutch housing or drum.
Many of these clutch constructions have a pair of arcuate-shaped clutch shoes which are pivotally mounted on a clutch backing plate and arranged in an end-to-end relationship with respect to each other. The backing plate in turn is fixed to a drive shaft or hub for rotation with the drive shaft. These clutch shoes have various spring arrangements which bias the shoes toward and retain the shoes in retracted position. It is this spring retaining tension which must be overcome by the centrifugal force before the clutch shoes engage the driven member.
Stop means must be provided on the clutch rotor to contact the clutch shoes upon their return to retracted position at a predetermined location with respect to the driven drum. Most known clutch constructions use a separate component which is attached in some manner to the backing plate or drive flange which is engaged by the clutch shoe upon its return to retracted position. These separate stop components require additional manufacturing steps and may present maintenance problems, all of which increase the cost of the clutch and reduce its efficiency and life span. Likewise, these separate stop components may restrict the use of the various types and configurations of backing plates which may be required for particular applications.
There is no known centrifugal clutch construction of which I am aware which provides shoe stops as an integral portion of the clutch shoe by forming an inwardly extending projection on the web of the shoe, preferably adjacent the pivotal mounting opening for the shoe, which projection engages the rotor hub, preventing further inward movement of the shoes by the tension springs.